Snail trails panels - damaged?

[kuranaga]

Hi

Ive a 250W that has developed some visible snail trails. It gives only 28Voc instead of 38Voc :/ It doesn't look that bad actually from outside so I wonder why the power output is so bad?!

Do snail trails always reduce power output that much?

link to pictures: https://postimg.cc/gallery/5C809J3

thanks

 

[rmaddy]

There have been a few posts on "snail trails". You may find the following search results helpful:

Search results for query: snail trails

diysolarforum.com

 

[pellicle]

When I bought my used panels, I found these, asked the seller (an installer) measured them (the panels) found them within spec (even though they were about 10 years old) and further to that did some research and found this article was the most sensible of what I found

Microscopy study of snail trail phenomenon on photovoltaic modules

Snail trails on photovoltaic modules are a source of enormous concern to the solar industry as no scientific reports on the mechanisms producing this global phenomenon were previously available. Here, for the first time, we clarify the origin of these snail trails as a product of the formation...

pubs.rsc.org

Here, for the first time, we clarify the origin of these snail trails as a product of the formation of silver carbonate nanoparticles which discolor the silver grid. Micropore arrays on the silicon substrate within the snail trail region could accelerate the discoloration by offering reactive compounds via penetration and release. The potential mechanisms of photovoltaic module discoloration are proposed, yielding clues as to how snail trail formation can be mitigated by technical solutions. Aging tests on the discolored modules suggest no significant power degradation or discolored area enlargement after accelerated aging.

 

[iamrich]

Do snail trails always reduce power output that much?

I have 250w Trina panels that have snail trails and the voltage is spot on with specs. It is hard to tell from the pictures, but it looks like your panel angle is very steep?

 

[kuranaga]

I have 250w Trina panels that have snail trails and the voltage is spot on with specs. It is hard to tell from the pictures, but it looks like your panel angle is very steep?

nope!

you seem to not have understood my question. Voc is far too low, Voc does not depend on the angle at all. Even with diffuse sunlight you should have the output voltage very close to Voc when no load is connected!

ps. the angle is about 15°, location west palm beach.

All I can discover is that bigger trail, 6th from rigth 2nd from top. Looks very metallic to me... Even with full sun I got a max of 120W out of the panel, far too low. Somehow it feels like half of the panel would have been shorted electrically - but how? Maybe some bypass diode burned through, could that somehow happen?

 

[pullin_gs]

nope!

you seem to not have understood my question. Voc is far too low, Voc does not depend on the angle at all. Even with diffuse sunlight you should have the output voltage very close to Voc when no load is connected!

ps. the angle is about 15°, location west palm beach.

All I can discover is that bigger trail, 6th from rigth 2nd from top. Looks very metallic to me... Even with full sun I got a max of 120W out of the panel, far too low. Somehow it feels like half of the panel would have been shorted electrically - but how? Maybe some bypass diode burned through, could that somehow happen?

Yes, Voc is too low. Panel has a physical defect someplace and should be replaced.